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Abstract:

In a method and apparatus for assisting the driver of a vehicle in
maintaining a traffic lane limited by traffic lane markings, the traffic
lane markings and the position of the vehicle in the traffic lane are
detected. Upon an actual or impending change of traffic lanes a lane
change warning is output to the driver of the vehicle in a first step,
and a course correcting actuating intervention counteracting the lane
change is carried out in a second step. The actuating intervention is
carried out only if the change of traffic lanes is impermissible due to
the type of traffic lane marking to be crossed during the traffic lane
change, or if the lane change is not possible without danger due to
collision-endangering objects present on the side of the traffic lane.

Claims:

1.-16. (canceled)

17. A driver assistance system for a vehicle, said system comprising: a
traffic lane recognition device for detecting a traffic lane driven on by
a vehicle, based on lane-limiting traffic lane markings; a warning device
for outputting a lane abandoning warning to a driver of the vehicle when
a lane abandoning tendency is detected; an object recognition device for
detecting lateral objects that are present next to the sensed traffic
lane; and a control device for carrying out a course correcting actuating
intervention; wherein, the traffic lane recognition device is configured
to recognize, based on a type of the traffic lane markings, whether an
abandonment of the traffic lane by passing over the particular traffic
lane marking is permissible or impermissible; the control device is set
up to trigger the actuating intervention subsequent to the output of the
lane abandoning warning; and the condition for triggering the actuating
intervention is that an abandoning of the traffic lane is impermissible,
or that the danger of a collision with a detected lateral object exists
with a permissible abandoning of the traffic lane.

18. The driver assistance system according to claim 17, wherein: the
object recognition device is set up to detect objects present forward of
the vehicle as objects in front; and the control device is set up to
suppress actuating intervention if an evaluation of the situation detects
existence of the danger of a collision with a sensed object in front.

19. The driver assistance system according to claim 17, wherein the
traffic lane recognition device is set up to judge an abandoning of the
traffic lane as permissible if the traffic lane marking that will be
passed over is a broken line, and to judge it as impermissible if the
traffic lane marking that will be passed over is a continuous line.

20. The driver assistance system according to claim 17, wherein the
control device is set up to carry out the actuating intervention by
individual braking of single wheels of the vehicle.

21. The driver assistance system according to claim 17, wherein the
warning device is set up to output the lane abandoning warning in the
form of steering wheel vibrations to the driver.

22. The driver assistance system according to claim 17, wherein the
object recognition device is configured to recognize standing and moving
objects outside and inside the traffic lane.

23. The driver assistance system according to claim 17, wherein the
control device is configured to suppress actuating intervention with a
permissible abandoning of the traffic lane, if an area is present that is
sufficiently large for a lane change.

24. The driver assistance system according to claim 17, wherein the
traffic lane recognition device is designed as a video-based lane
recognition system.

25. The driver assistance system according to claim 17, wherein the
object recognition device is designed as a radar system.

26. A method for assisting the driver of a vehicle in maintaining a
traffic lane that is limited by traffic lane markings, said method
comprising: detecting the traffic lane markings and the position of the
vehicle within the traffic lane; sensing the environment of the vehicle
for presence of collision-endangering objects next to the traffic lane;
and when the traffic lane is being abandoned or about to be abandoned,
either a lane abandonment warning is output to a vehicle operator, or a
course correcting actuating intervention acting against the lane
abandonment is carried out; wherein, the abandoning of the traffic lane
is judged to be permissible or impermissible based on the type of traffic
lane marking that is to be crossed over; the course correcting actuating
intervention is to be carried out chronologically after the output of the
lane abandoning warning; and the course correcting actuating intervention
is suppressed if the abandoning of the traffic lane has been judged to be
permissible and no collision-endangering objects are present next to the
traffic lane.

27. The method according to claim 26, wherein: an operating environment
of the vehicle is sensed for the presence of collision-endangering
objects in front of the vehicle in the traffic lane; and the course
correcting actuating intervention is suppressed if a
collision-endangering object is present in front of the vehicle in the
traffic lane.

28. The method according to claim 26, wherein abandonment of the traffic
lane is judged to be permissible if the traffic lane marking that is to
be passed over when abandoning the lane is a broken line.

29. The method according to claim 26, wherein abandonment of the traffic
lane is judged to be impermissible if the traffic lane marking that is to
be passed over is a continuous line.

30. The method according to claim 26, wherein: the magnitude of the
danger that a collision of the vehicle with one of the
collision-endangering objects is estimated; and the actuating
intervention is carried out depending on the estimated magnitude of the
danger.

31. The method according to claim 26, wherein the lane abandoning warning
is output as a haptic warning.

32. The method according to claim 26, wherein the course correcting
actuating intervention is carried out as a single wheel brake
intervention.

Description:

[0001] This application is a national stage of PCT International
Application No. PCT/EP2008/010007, filed Nov. 26, 2008, which claims
priority under 35 U.S.C. §119 to German Patent Application No. 10
2008 005 999.4, filed Jan. 25, 2008, the entire disclosure of which is
herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The invention relates to a driver assistance system and a method
for assisting the driver of a vehicle in maintaining a traffic lane
limited by traffic lane markings.

[0003] German patent document DE 694 02 278 T2 discloses a method of this
general type, in which the course of a traffic lane used by a vehicle is
detected by detecting traffic lane markings limiting the lane, and a
steering torque is exerted on a steering system of the vehicle if it
approaches one of the traffic lane markings, thereby assisting the driver
in maintaining the traffic lane. If the traffic lane marking is
subsequently crossed, the driver is informed by a haptic and acoustic
warning. The environment of the vehicle is additionally monitored for
collision-endangering objects with this method, and a lateral movement of
the vehicle is prevented or inhibited, if collision-endangering obstacles
are detected by the monitoring.

[0004] International patent document WO 2006/081936 A1 discloses a method
for supporting the driver of a vehicle in maintaining a lane, in which
the prospective deviation of the vehicle position from a nominal lane
determined by means of traffic lane markings is determined and a
supporting steering torque is generated when exceeding certain deviation
thresholds, which supports the driver when guiding the vehicle back into
the nominal lane. The deviation thresholds can thereby be varied in
dependence on objects, which are detected in the driving direction of the
vehicle laterally of the traffic lane driven on by the driver.

[0005] One object of the invention is to provide a driver assistance
system and method of the above-mentioned type, for helping the driver of
a vehicle to maintain a lane, wherein the supporting measures on the side
of the system take place in such a manner that they are perceived by the
driver as adequate and not as disturbing.

[0006] This and other objects and advantages are achieved by the driver
assistance system according to the invention, which comprises a traffic
lane recognition device for detecting a traffic lane driven on by the
vehicle by means of lane-limiting traffic lane markings, a warning device
for outputting a lane abandoning warning to a driver of the vehicle when
recognizing a lane abandoning tendency, an object recognition device for
detecting lateral objects which are present next to the detected traffic
lane and a control device for carrying out a course correcting actuating
intervention. The traffic lane recognition device is set up to recognize,
based on the type of the traffic lane markings, whether a traffic lane
change by passing over the traffic lane marking is permissible or
impermissible; and the control device is set up to trigger an actuating
intervention subsequent to the output of the lane abandoning warning when
such a lane change is impermissible, or when there is a danger of
collision with a detected lateral object.

[0007] According to the invention, therefore, support is offered to the
driver in several escalation steps: in a first escalation step, a lane
abandoning warning referring to the lane abandoning tendency is output
and in a subsequent second escalation step, a course correcting actuating
intervention acting against the lane abandoning tendency is carried out.
The second escalation step is thereby only activated under the condition
that the abandoning of the traffic lane is impermissible or is dangerous
due to a possible collision with lateral objects. This means, in
situations, in which the passing over the traffic lane marking is
permissible and also possible without danger, the second escalation step
is not activated and the course correcting actuating intervention is thus
not carried out. In these situations it is assumed that the driver will
deliberately want to leave the traffic lane and will perceive an
actuating intervention acting against the lane abandoning as an
inappropriate and unexpected system action, which would lead to
acceptance problems with frequent occurrence.

[0008] The object recognition is preferably set up in such a manner that
it can also detect objects that are in front in addition to lateral
objects, which objects that are in front are within the traffic lane in
front of the vehicle, and the control device is advantageously set up in
such a manner that it suppresses the actuating intervention, if an
evaluation of the situation results in that the danger of the collision
with a detected front object is present.

[0009] It can be prevented in this manner that an evasion maneuver carried
out by the driver for passing around an obstacle which is present in the
driving path of the vehicle is prevented or hampered by the actuating
intervention that takes place on the system side. The driver can thus
evade a front object recognized as an obstacle and can thereby leave the
traffic lane without a counter-reaction on the system side, even if an
abandoning of the traffic lane would be impermissible.

[0010] The traffic lane recognition device is preferably set up to judge
the abandoning of the traffic lane as permissible if the traffic lane
marking that is being passed over is a broken line, and to judge it as
impermissible if the traffic lane marking being passed over is a
continuous line.

[0011] The control device is preferably arranged to carry out the
actuating intervention by individual braking of individual wheels of the
vehicle.

[0012] In an advantageous arrangement of the driver assistance system, the
warning device is set out to output the lane abandoning warning in the
form of steering wheel vibrations to the driver.

[0013] In a further advantageous arrangement of the driver assistance
system, the object recognition device is set up to recognize standing and
moving objects outside the traffic lane.

[0014] The control device is preferably set up to suppress the actuating
intervention with a permissible abandoning of the traffic lane, if an
area that is sufficiently large for a lane change is present next to the
traffic lane.

[0015] The traffic lane recognition device is preferably designed as a
video-based lane recognition system.

[0016] The object recognition device is preferably arranged as a radar
system.

[0017] With the method according to the invention for supporting the
driver of a vehicle in maintaining a traffic lane limited by traffic lane
markings, the traffic lane markings and the position of the vehicle
within the traffic lane are detected, the environment of the vehicle is
sensed for the presence of collision-endangering lateral objects next to
the traffic lane, and when abandoning or an impending abandoning of the
traffic lane, a lane abandoning warning is output to the driver, and a
course correcting actuating intervention acting against the lane
abandoning is carried out. The course correcting actuating intervention
is carried out chronologically after the output of the lane abandoning
warning; the abandoning of the traffic lane by means of the type of the
traffic lane marking to be passed over hereby is furthermore judged to be
permissible or impermissible; and the course correcting actuating
intervention is suppressed if the abandoning of the traffic lane has been
judged to be permissible and no collision-endangering lateral objects
have been recognized next to the traffic lane.

[0018] The environment of the vehicle is further examined for the presence
of collision-endangering front objects which are in front of the vehicle
within the traffic lane, and the course correcting actuating intervention
is suppressed if such a collision-endangering front object is recognized
a present.

[0019] The actuating intervention is thus suppressed in situations, in
which one can assume that the driver abandons the traffic lane
deliberately, in order to evade a collision-endangering object in front
recognized as an obstacle.

[0020] The abandoning of the traffic lane is thereby preferably judged to
be permissible if the traffic lane marking to be passed over when
abandoning the lane is a broken line.

[0021] The abandoning of the traffic lane is preferably judged to be
impermissible if the traffic lane marking to be passed over when
abandoning the lane is a continuous line.

[0022] In an advantageous further development of the method, it is
estimated how high the danger of a collision of the vehicle with one of
the collision-endangering lateral objects is when abandoning the lane,
and the actuating intervention is carried out in dependence on the
estimated height of the danger.

[0023] In an advantageous further development, the lane abandoning warning
is output as a haptic warning.

[0024] In a further advantageous further development of the invention, the
course correcting actuating intervention is carried out as a single wheel
brake intervention.

[0025] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed description of
the invention when considered in conjunction with the accompanying
drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a block diagram of the driver assistance system according
to the invention;

[0028]FIG. 3 shows a typical traffic situation on a road with oncoming
traffic;

[0029]FIG. 4 shows a typical traffic situation on a road with an
impermissible lane change.

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] Parts corresponding to each other are provided with the same
reference numerals in all figures.

[0031]FIG. 1 shows a driver assistance system 1 for a vehicle, with a
traffic lane recognition device 10, a warning device 11, an object
recognition device 12, a control device 13, an actuating device 14 for
controlling the lateral movement of the vehicle and a state detection
device 15 for detecting the displacement state of the vehicle.

[0032] The traffic lane recognition device 10 may be a video-based
recognition system, which records video images of a road section in front
of the vehicle and uses image processing to recognize traffic lane
markings that are applied to a road driven on by a vehicle for the
traffic lane limiting. The device 10 determines the course of the traffic
lane driven on by the vehicle and the position of the vehicle within the
traffic lane by means of the recognized traffic lane markings. The
traffic lane recognition device 10 further recognizes, by means of the
type how traffic lane markings are designed, if it is permissible or
impermissible to pass over these. Passing over a traffic lane marking is
usually impermissible if it is designed as a continuous line, and
permissible if it is designed as a broken line. With traffic lane
markings designed as a double line, the type of the inner line is thereby
relevant for the decision if it is permissible or impermissible to pass
over these. The determined information regarding the course and the type
of the traffic lane markings and with regard to the position of the
vehicle in the traffic lane are passed to the control device 13 by the
traffic lane recognition device 10 as lane information SL.

[0033] The object recognition device 12 is designed as a radar system,
which has several radar sensors distributed at the vehicle, which are
aligned to the front, the rear and to the sides of the vehicle, and which
are suitable to detect standing and moving lateral and front objects that
are present outside the traffic lane driven on by the vehicle immediately
next to the vehicle, laterally in front of the vehicle and laterally
behind the vehicle or in front of the vehicle within the traffic lane
driven on by the driver. The object recognition device 12 is thereby in
the position to recognize stationary obstacles outside the traffic lane
being driven on, in particular guard railings or other constructions,
plants and parking vehicles, but also vehicles which come close to the
vehicle from an adjacent opposite traffic lane or which come close to the
vehicle from behind on an adjacent lane and enter its dead angle. The
object recognition device 12 is also in the position to recognize
vehicles and stationary obstacles which are present in front of the
vehicle within the traffic lane driven on by the vehicle.

[0034] The object recognition device 12 determines the distance and the
speed of the lateral or objects in front and passes this information as
object information SO to the control device 13.

[0035] The state sensing device 15 comprises sensors for determining the
speed of the vehicle and of the steering angle or of the yaw angle of the
vehicle and passes this information as state information to the control
device 13.

[0036] The control device 13 determines by means of the lane information
SL, the object information SO and the state information SZ, if a lane
abandonment is present and outputs a warning signal SW to the warning
device 11 if this is the case, which then outputs a traffic lane
abandoning warning to the driver of the vehicle. The warning device 11 is
advantageously designed as a haptic warning device, which effects a
vibration at the steering wheel of the vehicle that can be sensed by the
driver. An acoustic or optical warning can also be output to the driver
as a further traffic lane abandoning warning.

[0037] The control device further determines by means of the lane
information SL, the object information SO and the state information SZ if
the lane abandoning tendency is further present subsequent to the output
of the lane abandoning warning after a predefined reaction time. If this
is the case, the driver has not reacted or not reacted sufficiently to
the lane abandoning warning, and an actuating signal is then output to
the actuating device 14, which controls the lateral displacement of the
vehicle in the sense of a reduction of the lane abandoning tendency.

[0038] The actuating device 14 is designed as a brake control device in
the present embodiment, which generates a yaw moment acting against the
lane abandoning tendency by means of a defined single wheel braking. The
actuating device 14 can additionally or alternatively also be formed as a
steering control device, which exerts a steering torque acting against
the lane abandoning tendency on a steering system of the vehicle.

[0039] The control device 13 is set up to suppress the actuating signal SE
if certain intervention fading conditions are fulfilled. The details for
this will be explained further by means of FIGS. 2 and 3.

[0040]FIG. 2 shows a road with two traffic lanes Se, Sn limited by
traffic lane markings S1, S2, S3 and with two vehicles F1, F2 driving in
respectively one of the traffic lanes Se in a schematic depiction. The
two outer traffic lane markings S1, S3 are designed as continuous lines
and the center traffic lane marking S2 is designed as a broken line.
Passing over of the outer traffic lane markings S1, S3 is thereby
impermissible and a passing over of the center traffic lane marking S2 is
permissible.

[0041] The vehicle F1 is equipped with the driver assistance system 1. It
drives within the traffic lane Se, which is referred to as an own traffic
lane, and is there within a driving path K which is limited by fictitious
limiting lines S10, S20. The driving path K represents the desired space
of the vehicle F1 with the own traffic lane Se. The limiting lines S10,
S20 can be displaced in dependence on the speed and/or in dependence on a
driver input, they can in particular be displaced in such a manner that
they correspond with the positions of the lane markings S1, S2. The
vehicle F1 moves with a speed v1 represented by an arrow.

[0042] The vehicle F2 is in the traffic lane Sn adjacent to the own
traffic lane Se and approaches the vehicle 1 from behind. The speed v2
and the driving direction of the vehicle F2 is indicated by an arrow. The
vehicle is in the sensing region of the object recognition device 12 and
is detected thereby as a moving lateral object.

[0043] Next to the own traffic lane Se is a guard railing O1, which is
detected by the object recognition device 12 as a standing lateral
object.

[0044]FIG. 3 also shows a road with two traffic lanes Se, Sn limited by
traffic lane markings S1, S2, S3 and with two vehicles F1, F3 driving in
respectively one of the traffic lanes Se,Sn in a schematic depiction. The
vehicle F3 is in front of the vehicle F1 on the traffic lane Sn adjacent
to the own traffic lane Se and drives in this traffic lane Sn with a
speed v3 represented by an arrow.

[0045]FIG. 4 also shows a road with two traffic lanes Se, Sn limited by
traffic lane markings S1, S2', S3 with the vehicle F1 driving in the
traffic lane F1 and with an object O2 in front of the vehicle F1 in the
traffic lane Se. The object O2 in front, for example a standing or slowly
moving vehicle, is an obstacle for the vehicle F1, that is, a
collision-endangering object, with which the vehicle F1 will probably
collide within an anticipatory period, if no countermeasures are resorted
to. The driver of the vehicle F1 wants to evade this
collision-endangering object O2 in front and drive over the traffic lane
marking S2' for this. The latter is designed as a continuous line, that
is, a passing over the traffic lane S2' is impermissible. In such a case,
only a lane abandoning warning shall be output, and an actuating
intervention acting against the evasion maneuver shall be suppressed.
This means that the driver will have the full responsibility for the
handling of the dangerous situation caused by the object O2 in front.

[0046] The control device 13 carries out an evaluation of the situation by
means of the provided object information SO, in order to determine if the
sensed lateral objects F2, F3, O1 or objects O2 in front are
collision-endangering objects, that is, to determine if the sensed
lateral objects F2, F3, O1 represent a collision danger in the case that
the vehicle F1 will leave the own traffic lane Se, or to determine if the
sensed objects O2 in front represent a collision danger in the case that
the vehicle F1 will not leave the own traffic lane Se.

[0047] The vehicle F2 nearing the vehicle F1 in the dead angle region is
thus for example evaluated as a collision-endangering object if it is
within a predefined distance region behind the vehicle F1 and draws
nearer to the vehicle F1 with a high speed v2 (that is, with a speed v2
that is larger than the speed v1 of the vehicle F1 by a predefined
threshold value). The oncoming vehicle F3 is evaluated as a
collision-endangering object if its trajectory determined in an
anticipatory manner crosses the trajectory of the vehicle F1, also
determined in an anticipatory manner, in a position, which the two
vehicles F1, F3 will reach simultaneously with an unchanged maintenance
of their movement states. The guard railing O2 is correspondingly
evaluated to be a collision-endangering object if the trajectory of the
vehicle F1 will contact the guard railing O1.

[0048] If one of the lateral objects F2, F3, O1 is evaluated as a
collision-endangering object, the control device 13 can additionally
assign a danger measure to the respective object 13 which indicates the
magnitude of the probability of the collision or the strength of the
collision.

[0049] A sensed front object O2 is for example evaluated as a
collision-endangering object if an evaluation of the situation by means
of the distance and the relative speed between the vehicle F1 and the
sensed front object O2 determines that a collision will result within a
predefined period, if the vehicle F1 should be kept in the traffic lane
Se with an unchanged relative speed, or that the time which remains as a
maximum action period for the driver to just avoid a collision by
initiating a collision-avoiding measure, in particular a full brake
application or an evasion maneuver, is smaller than a predefined time
threshold.

[0050] The control device 13 determines by means of the state information
SZ, in particular by means of the speed v1 of the vehicle F1 and by means
of a steering angle adjusted at a steering system of the vehicle F1 the
trajectory of the vehicle F1 in an anticipatory manner for an
anticipatory period or an anticipatory distance. This is a predicted
displacement lane, along which the vehicle will move during the
anticipatory period or until reaching the anticipatory distance. The
control device 13 then determines a period TLC ((time to line crossing),
which the vehicle will presumably need to leave the driving path K (that
is, the period that the vehicle F1 will need to reach the position F'
shown in dots, in which the limitation line S20 of the driving path K is
passed over). This period is referred to as lane abandoning period TLC in
the following.

[0051] The control device 13 subsequently compares the determined lane
abandoning period TLC with a predefined time threshold. If the lane
abandoning period TLC is smaller than the predefined time threshold, the
control device 13 determines that the vehicle F1 has a tendency to
abandon a lane and then outputs the lane abandoning warning in a first
escalation step to the driver of the vehicle F1 via the warning device
11. The control device 13 further determines if the lane abandonment
tendency within a predefined reaction time exists further after the
output of the lane abandoning warning. If this is the case, the actuating
signal SE is output to the actuating device 14, in order to move the
vehicle F1 back into the driving path K by a course correcting actuating
intervention carried out by the actuating device 14.

[0052] The actuating signal SE is advantageously generated in dependence
of the danger measure assigned to the corresponding object in such a
manner when determining a collision danger with one of the lateral
objects, that the actuating intervention carried out by the actuating
device 14 is carried out at a stronger measure with a high measure of
danger and/or is initiated earlier than with a small measure of danger.
An adaptation of the actuating intervention to the criticality of the
traffic situation resulting when abandoning the lane is thus obtained. An
adaptation of the actuating intervention to the criticality of the
traffic situation resulting when abandoning the lane is obtained thereby.

[0053] The output of the actuating signal SE is however suppressed if the
following intervention fade-out conditions are fulfilled: [0054] a) the
control device 13 has obtained the information from the traffic lane
recognition device 10 that a passing of the corresponding traffic lane
marking S2 is permissible, that is, that the traffic lane marking S2--as
shown in FIGS. 2 and 3--is designed as a broken line, and the control
device 13 has additionally determined in advance by means of the
conducted evaluation of the situation that a collision danger with one of
the sensed lateral objects F2, F3, O1 does not exist when abandoning the
lane, or [0055] b) the control device 13 has determined in advance by
means of the conducted evaluation of the situation that the danger of a
collision with a detected object O2 in front exists when maintaining the
vehicle F1 in the traffic lane Se.

[0056] The condition for the triggering of the second escalation step is
thus the previous output of the lane abandoning warning in the first
escalation step and the determination that an abandoning of the traffic
lane Se due to the type of the design of the traffic lane marking S1, S2
to be driven over is hereby impermissible or that the danger of a
collision with one of the sensed standing or moving lateral objects F1,
F3, O1 cannot be excluded with a permissible abandoning of the traffic
lane Se, as additionally the determination that the danger of a collision
with a sensed standing or moving object O2 in front does not exist.

[0057] The foregoing disclosure has been set forth merely to illustrate
the invention and is not intended to be limiting. Since modifications of
the disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the art, the invention should
be construed to include everything within the scope of the appended
claims and equivalents thereof.

Patent applications by Bernd Danner, Aichtal DE

Patent applications by Uli Kolbe, Stuttgart DE

Patent applications by Daimler AG

Patent applications in class Internal alarm or indicator responsive to a condition of the vehicle

Patent applications in all subclasses Internal alarm or indicator responsive to a condition of the vehicle